The present invention relates to an assembly for observation and for laser interferometric measurements, in particular of thin-film structures, for example semiconductor structures such as integrated circuits.
A plasma-etch control system, intended more particularly for integrated-circuit board diagnostics, in which the etching operations on the thin films are controlled by means of an interferometric detection system using the beam of a laser tube, is known. A video camera moreover enables the position of the spot produced by the laser beam on the integrated-circuit board to be adjusted and monitored.
The main drawback of this known system consists in that the laser tube and the video camera are separate, which renders the assembly bulky and difficult to house in a plasma-etch apparatus and especially in an apparatus for producing integrated circuits, above which the space available is very restricted. In addition, this known system uses a single laser, which is insufficient for some applications.